supports ---@field name? type

Author: sumneko

syntaxes/lua.tmLanguage.json

@@ -501,10 +501,13 @@
 					"end": "(?=\\n)",
 					"patterns": [
 						{
-							"begin": "\\b([a-zA-Z_][a-zA-Z0-9_]*)\\b",
+							"begin": "\\b([a-zA-Z_][a-zA-Z0-9_]*)\\b(\\??)",
 							"beginCaptures": {
-								"0": {
+								"1": {
 									"name": "entity.name.variable.lua"
+								},
+								"2": {
+									"name": "keyword.operator.lua"
 								}
 							},
 							"end": "(?=\\n)",